need info guys,,,,
want to get a prus cyl head but cant decide aluminum or cast iron.Besides the weight savings , what are other differences.
You wont have the corrosion issues with iron that you have with aluminum don't ask how I know about that . Other than that I don't know the particular head, but based on my experience I'll stay with iron from here on out.
Aluminum heads mostly gives corrosion issues when used without a fresh antifreeze mix of glycol with corrosion inhibitors and water.
I haven't seen the cast iron version of the Prus head myself, but based on others reports it seems to be the same shape as the alu version with the same approx. 5:1 compression.
It's a good head with better quality than the Z head (the area above the pistons is machined on Prus heads), slightly more power at the high end than the Z, but the price is $100 more for the cast iron version and it weighs almost three times more.
The P head is vacuum impregnated. I believe the Sherman head is impregnated however I cant confirm that. The other heads out there are not impregnated to my knowledge.This technology is used by all the automobile manufactures today with aluminum heads and blocks. It is also used with cast iron. All heads are precision machined and pressure tested before they are sent out. Therefore no coolant leaks. My new Ford diesel has aluminum heads on it. It has a monitor to check your engine coolant additive to see when your PH levels are high. They do this to reduce corrosion. Aluminum or cast iron is up to the individual.
Like Kevin, we also vacuum impregnate all our RAJO cylinder heads twice after the CNC machining process has been completed. Our cylinder heads are cast from 356 aluminum alloy and heat treated to T6. Like all aluminum castings, you will have some porosity. We pressure test each machined RAJO cylinder head to 40 PSI with straight green anti-freeze. We note any minor weeping and then treat with the chemical wash and then proceed with the vacuum impregnation process. Once the process has been completed, we pressure check the head again to ensure no leaks. About 10% of the cylinder heads we have tested prior to the vacuum impregnation process have had very minor weeping due to a microscopic porosity here and there. Well worth the added cost to ensure a quality product. We currently use IMTECH for our vacuum impregnation process and are please with the results. You can learn more by reviewing the information on their website www.imtech-inc.com. Like Roger stated above, you must maintain the proper mix of anti-freeze to ensure corrosion does not damage the cylinder head.